This invention relates to apparatus for the wet treatment of tubular knitted textile material, comprising at least one nozzle for supplying a stream of air to the textile material, and devices for retaining an air bubble formed in the material, for measuring this air bubble and for controlling the air supply.
Various devices are known for the wet treatment (such as dyeing, washing or rinsing) of tubular knitted textile material which blow air by means of nozzles onto or into the strands in order to open or spread the wet strands, which tend to cling together. Spreading the strands is necessary to facilitate the next wet treatment or drying operation. In one known apparatus of this type U.S. Pat. No. 3,508,286 to Rosen; also German Offenlegungsschrift No. 1,760,268, the air bubble formed by blowing a stream of air into the textile material is held back by two rollers of which one is fixedly arranged and the other is mounted for movement. The movable roller is deflected to a greater or lesser extent, depending on the size of the air bubble, activates a control switch and, hence, influences the stream of air blow into the textile material.
Extensive tests conducted by the applicants have shown that this known apparatus is not satisfactory in operation. Since one of the two above-mentioned rollers has to be movable to perform its function, the two rollers are not able satisfactorily to hold back the air bubble formed under all operational conditions. Instead, under a sudden insurge of air under pressure, the air bubble suddenly assumes such a size and the movable roller is thus momentarily deflected to such an extent that part of the air bubble slips through between the two rollers. To eliminate this fault, the air supply may have to be briefly switched off.